To: Buckley Rumford
Date: November 8, 2003
I really like your site. I've only known about Rumford fireplaces for a few days, but I am very interested in putting one in a house that I'm hoping to begin re-building in the spring. (Incidentally, the Rumford-style fireplace I saw was in the Fine Homebuilding book - "Small Houses"). I did have a quick question though:
A friend's parents live in an old Queen Anne (Victorian) house in North Carolina (c1890) that's equipped with a number of coal fireplaces. I've been down there a number of times in the winter and was shocked at how well they worked - even when used with smallish pieces of wood instead of coal. Once lit they draw extremely well, which I suppose shouldn't be surprising b/c it an old (leaky) house with tall chimneys. The fireplaces also put out intense amounts of heat.
One of the interesting design features was that the back wall of the firebox slanted noticably towards the room. At the bottom of the opening, it was maybe 24" deep, but at the top near the lintel, it was only 6" deep. As a result, the flames flowed right up against the firebrick as they made their way up to the chimney. Also as a result, the flames were very close to the room at the point when they disappeared behind the lintel. And no smoke entered the room whatsoever. It seemed as if the "slanted-ness" of the rear wall contributed both to the intense heat as well as to the powerful draw of the chimney. By contrast, Rumfords appear to have vertical walls in their fireboxes.
Has anyone that you know of ever tried to incorporate this "slanted" characteristic into the Rumford design? Is there any reason to think that it would be unsatisfactory? Any other comments/ideas? Thanks,
You've made an interesting observation, especially for someone only recently aware of Rumford. And yes, you're not the first to ask the question about slanted firebacks.
Most of the Victorian era fireplaces were patented variations of the original Rumford fireplace which was common up until about 1850. Some of the "improvements" might have at least done little harm but most were primarily marketing ploys and the "improvements" were made in order to obtain patents.
The history of the "slanted fireback" dates from a footnote in Rumford's 1796 essay and many slanted-back Rumford variations were and still are built. See my article at http://www.rumford.com/articleOrton.html.
We've chosen to stick with the traditional Rumford design recommended by Rumford - not try to "improve" the design as so many have failed to do in the last 200 years. I would never say the Rumford couldn't be improved but to slant the back usually requires that the throat be opened up a little, especially if the streamlining is neglected as it often is in these variations, in order to make the fireplace draw. Maybe you get a little more reflected radiant heat from the slanted back but you'd also waste more heated air up the chimney to make it draw.
We've tested our traditional Rumford in a test lab to measure efficiency and emissions but so far no slanted back Rumford variation has been tested so we can't really make any scientific comparisons. I should say there has been a Rosen and a modified Rumford tested for emissions but only with the doors closed so, to me that obviates the whole reason for building an open reflective radiant heating Rumford and tells us nothing about the performance of these fireplaces without doors.
I suspect that your Queen Anne fireplaces work well and are well designed compared with modern poorly designed fireplaces. They probably draw well despite the lack of streamlining in the throat due to their small size and tall chimneys. Would they be improved if the firebacks were rebuilt straight and the throats rounded and made smaller according to Rumford's suggestions? I think so, but for ten or twenty thousand dollars you could probably test them both ways and prove it one way or another.
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